Dyna-lap question...

[Dom Franco]

I have a question for any of you who have ever built a Dyna-lap steel guitar.

I want to fabricate a stepped tuner headpiece out of wood like a dyna-lap.

Are they just glued on to the body of the guitar, or are there little nails or screws used?

It doesn't seem like glue alone would be strong enough to withstand the stress of all the string tension?

One more question, What type of glue would be the strongest? I am using purplewood and Ash...
Thanks
Dom Franco

[Don McGregor]

Dom,
I am constantly amazed at how many makers use a similar design, without string pressure yanking it right off the neck first time out.
I, too, am going to try this design soon with a piece of Coco Bola I have. This wood is very hard, and hard to work. Apparently, Maple, and many other close grain hardwoods will work fine.
I'm thinking to use glue as well as two through bolts for each side.
I do know that, when using some exotic woods, like Teak, or Rosewood, for instance, you must first clean the natural oils off of the surfaces to be glued with Acetone.
In woodworking, when I want a permanent, glued joint, I use Titebond II. Articles in Fine Woodworking comparing glues have covered independent studies where Titebond II has out performed the others in actual glue joint shear tests.
If the surfaces are flat and clean, and proper directions are followed for spreading the glue and clamping, it should hold fine.
I hope some of the guys who use this type of keyhead will chime in with more experienced advice.
This is something I want to know more about.

[Mike Harris]

I see no evidence of bolts on my Dynalap, but there is obvious glue.

I hope that's helpful.

[Tom Pettingill]

Are they just glued on to the body of the guitar, or are there little nails or screws used?

It doesn't seem like glue alone would be strong enough to withstand the stress of all the string tension?

I can't speak to the Dynalap directly, but I can tell you that it is true that a properly done glue joint can be stronger than the surrounding wood.

I prefer regular old Tightbond original, and besides hot hide glue, it is one of the most popular amongst the luthier community. The problem with the "new and improved" versions is that they have additives / formulations to make them moisture / water resistant / waterproof. The result is that while they can form a strong bond, they actually cure a little softer which can dampen vibrations to a degree and also the joint under stress can creep over time. Unless you plan on storing your steel outside in the rain, waterproof glues are of no benefit.

Preparation of the joint is also very important. The best joint is freshly planed and perfectly flat and true with is mating surface. Regular type woodworking glues are very strong, but they are very poor at gap filling. Sanded joints are a bad idea especially for a small surface area under stress. Besides it being virtually impossible to get a perfectly flat surface by sanding, a cut wood fiber glues better than one ground down. If you absolutely have to sand something, use a hard flat block and only sand in one direction followed up by scraping the surface down with a cabinet scraper or razor blade. Finish up with blowing all dust and debris out of the pores with compressed air.

It might sound like I'm a little OCD about my glue joints and maybe I am, but I build my stuff to last generations. The extra care I take now means my steels have a much better chance of being around long after I'm gone from this world.
The inlay in this headstock is 30,000 year old mammoth ivory, I'm shooting to add at least another 100 years to that total.

.

[George Piburn]

edit

[Mark Vinbury]

Dynalap tuner blocks are glued on with Tightbond and good even clamping pressure, As far as I know, none have come unglued. I have a prototype that is 6 years old and was glued with Elmers Carpenters glue and it hasn't let go in spite of my cranking the wrong gauge strings up and down to try out different tunings. I think the bigger issue with this arrangement is the wood splitting horizontaly along the line of holes. This has happened to a couple that suffered shipping mishaps. I won't use anything but hard maple since I feel the grain is somewhat "homogenized" and less porous. I've had purpleheart and walnut bridge cradles split. Just seems like maple is the better wood for the job.

[David Ball]

If you think about it, the bridges on every Martin, Gibson, etc. etc. flat top guitar is held on with nothing but glue. It's strong stuff if it's done right.

[Danny Hammers]

Mark
Not heard from you lately
Just wanted to say Hi!

Danny Hammers

[Gary Meixner]

Dom,

For what it is worth I work for a company that formulates epoxy based adhesives and coating for the marine and woodworking industries. I agree with the resposnes so far and would add that both Elmers and original Titebond are very strong adhesives and would work just fine. Both require that the glue surfaces fit well with no gaps. Tom's points are very good but be careful not over work the glueing surfaces leaving it polished. Glue must be allowed to penetrate into the wood fibers. Spread the adhesive on both surfaces and let it sit for five minutes or so before clamping. Clamp firmly and let it set overnight. Oily woods like Rosewood and Cocbola should be cleaned just prior. Our tests show that isopropyl alcohol is a better choice than acetone. Acetone evaporate so fast that it tends to re-deposite the oils rather than carry them away. Now of course a good epoxy adhesive would be a great choice and some are better than others for use on difficult to bond woods like Cocobola, White Oak, Teak etc. Epoxy however favors a slightly rough gluing surfacea and a slight gap is better. Avoid excesive clamping pressure or you run the risk of squeezing all of the adhesive out of the joint. It is surprising how strong all these adhesives are. There is a lot more to the story and if anyone has specific questions I would be happy to answer them. I don't want to turn this into a commercial but I will recommend two products that we manufacture: T-88 and GelMagic from System Three Resins, Inc. Good luck,

Gary